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  1. #1
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    Novice rebuilder. 54k miles N54 crazy to rebuild now?

    Hi all,
    First disclaimer, I'm a very novice engine rebuilder having build a couple of small Honda K20s and a M54 a few years back. To my knowledge all 3 engines are still running well with their current owners Click here to enlarge Click here to enlarge.

    I've found myself with a complete 135i with 110k on it and picked up a bargain N54 motor + turbos for a price I couldn't resist (it seems healthy and compression is good).

    Would I be crazy at this point to rebuild the 54k motor with so 'few' miles with a view to swapping it into my 135i? I would want to do the rebuild myself (sending parts out for machining to an experienced local shop)?

    I think it might be a nice project and having a 0 miles fresh motor ready to go for when the 110k motor starts to misbehave seems like a useful thing?

    Thoughts.

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    I would do a leakdown test and if all goes well leave it alone. I just don't think the risk is worth the reward. Your 110k motor "should" last a while. You never know you may crash the car or decide to sell it. Before putting it in I would do gaskets/seals.

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    Click here to enlarge Originally Posted by blaster3500 Click here to enlarge
    I would do a leakdown test and if all goes well leave it alone. I just don't think the risk is worth the reward. Your 110k motor "should" last a while. You never know you may crash the car or decide to sell it. Before putting it in I would do gaskets/seals.
    Thank you. Makes sense, I need to fully assess the condition of the 54k motor, and replacing the head gasket and engine seals (main seals , gasket pans and the like) makes good sense too.

    If I do upgraded internals then this would change the decision presumably?

    Will do the leakdown test asap.

    An additional benefit to my situation is I have two 'spare' stock turbos with 54k on them also...which seems like a good place to be.

    Thanks

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    Do you plan on going past 500whp? That would be the only reason to upgrade internals. And there should be no reason to replace the head gasket unless you know there is a leak.

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    Id go farther, no point unless you plan on over 600. I personally feel 600hp is a fairly healthy spot for the daily driver n54. Racing often, eh i might think about it. And i wouldn't rebuild at all unless at the very least upgrading to forged pistons with more big boost friendly piston ring end gaps. And i probably wouldn't do pistons without rods cause hell, your in there already. Keep in mind, with a n54. There's about $1000 in consumables that goes with rebuilding the motor. By that i mean, gaskets, bolts, seals, sealer, bearings, etc. Definately not as cheap as say a honda or sbc
    2008 BMW 535i SPORT | FBO+ | VTT GC LITES | JB4 | DPT BEF | BMS METH KIT | PROMETH DP KIT | PR COILS

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    Click here to enlarge Originally Posted by Weehe Click here to enlarge
    Do you plan on going past 500whp? That would be the only reason to upgrade internals. And there should be no reason to replace the head gasket unless you know there is a leak.
    I think 500whp would likely be the upper limit of what I'd want to do in truth. This will be a weekend/fun car only so having some kind of 'not totally insane' would be sensible.

    So it looks like the consensus so far is largely a 54k motor with know known faults could should mostly be left alone (unless I had need to upgrade the internals which looks like I don't), .

    Looks like it's just going to be a complete inspection (borescope etc), renew the seals, and a fresh valve cover gasket (PCV stuff etc).

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    If 500 really is your upper limit? Then yeah, replace all the rubber and enjoy
    2008 BMW 535i SPORT | FBO+ | VTT GC LITES | JB4 | DPT BEF | BMS METH KIT | PROMETH DP KIT | PR COILS

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    Click here to enlarge Originally Posted by Tuppidsay Click here to enlarge
    If 500 really is your upper limit? Then yeah, replace all the rubber and enjoy
    Click here to enlarge Now you are making me doubt myself. Surely everything starts getting tougher above 500...cooling, oil etc etc, that's all going to need upgrading too?

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    Click here to enlarge Originally Posted by CastleBravo Click here to enlarge
    Click here to enlarge Now you are making me doubt myself. Surely everything starts getting tougher above 500...cooling, oil etc etc, that's all going to need upgrading too?
    Only if you are going 30+ minute sessions at the track. 500whp is pretty standard.

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    Click here to enlarge Originally Posted by Weehe Click here to enlarge
    Only if you are going 30+ minute sessions at the track. 500whp is pretty standard.
    Thanks much appreciated. Seems the people have spoken. I'll check the health of the engine and turbos. Change the rubber and keep it as is! The rebuild project can wait until it's actually needed.

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    Click here to enlarge Originally Posted by CastleBravo Click here to enlarge
    Thanks much appreciated. Seems the people have spoken. I'll check the health of the engine and turbos. Change the rubber and keep it as is! The rebuild project can wait until it's actually needed.
    Good choice! Hopefully the current setup lasts a long while as well.

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    While I doubt you will have any issues with the currently installed motor. One additional item would be to replace the rod bearings in the new motor since I'm guessing you will have the oil pan off the replace the gasket.

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    Click here to enlarge Originally Posted by Weehe Click here to enlarge
    While I doubt you will have any issues with the currently installed motor. One additional item would be to replace the rod bearings in the new motor since I'm guessing you will have the oil pan off the replace the gasket.
    100%. It's going to be on an engine stand until I complete the work and decide what vehicle to put it into.

    Regarding the rod bearings it sounds like a good idea. We are talking the 'big end' bearings right? I shouldn't be expecting any journal wear so a standard size like for like replacement would be okay?

    Where is a reliable source for measurements and tolerances of the journals? BMW docs? Bentley manual?

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    I'm currently rebuilding a engine. Just keep in mind that that fully tearing it down and reassembling it is a little bit over a $1,000. Make sure you don't toss the most likely good bearings in the trash because Oem bearings are about $33 a half bearing.

    I'm throwing some ebay piston rings(because and having a shop help me with bearing clearances. Currently, it's still cheaper to go this route than to chance a $#@!ty engine out of a crashed car.
    08' BMW 335xi, 153k Miles

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    Click here to enlarge Originally Posted by CastleBravo Click here to enlarge
    Regarding the rod bearings it sounds like a good idea. We are talking the 'big end' bearings right? I shouldn't be expecting any journal wear so a standard size like for like replacement would be okay?

    Where is a reliable source for measurements and tolerances of the journals? BMW docs? Bentley manual?
    I can't find any specs other than a image of a crushed plastigauge in a workshop manual. However, you can order bearings by looking the crank and the rod caps for the markings which indicate what bearing to use. https://www.newtis.info/tisv2/a/en/e...arings/GbBVRRF
    08' BMW 335xi, 153k Miles

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    Click here to enlarge Originally Posted by kylerwinterd Click here to enlarge
    I can't find any specs other than a image of a crushed plastigauge in a workshop manual. However, you can order bearings by looking the crank and the rod caps for the markings which indicate what bearing to use. https://www.newtis.info/tisv2/a/en/e...arings/GbBVRRF
    Yeah I'm in no hurry to get this engine rebuilt, it's just if it's worth it at 54k. It seems like beyond doing the seals, rubber gaskets and maybe the big end bearings it's probably not worth a full rebuild. I need to check the whole engine over as if I need valve stems or anything like that that's going to require a new head gasket so that could change the situation.

    Re tolerances, when I rebuilt an M54 a few years ago the crank and rod journals were out of spec and hand to be ground down, which then required oversized shells....without some reference to what the N54 crank should measure it's going to be guess work.

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    1 out of 1 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by CastleBravo Click here to enlarge
    Yeah I'm in no hurry to get this engine rebuilt, it's just if it's worth it at 54k. It seems like beyond doing the seals, rubber gaskets and maybe the big end bearings it's probably not worth a full rebuild. I need to check the whole engine over as if I need valve stems or anything like that that's going to require a new head gasket so that could change the situation.

    Re tolerances, when I rebuilt an M54 a few years ago the crank and rod journals were out of spec and hand to be ground down, which then required oversized shells....without some reference to what the N54 crank should measure it's going to be guess work.
    newtis.info has the data you are looking for... but, slap in some new bearings and use some plasti-gauge on the journal. If it comes back between .0015" - .002" you're good. Re-seal the oil filter housing and oil pan. I wouldn't bother touching anything else. The front/rear main seals really don't fail unless you have a pcv issue. if you want to do the valve cover gasket then just buy a whole new generic valve cover. For 500whp goal I would not do much else to the engine itself. They are <$2k used don't overthink it and turn a cheap used engine into a money pit.

    If you want 700whp+ then you are now talking about rod, pistons, and messing with machine work. Gets very expensive quick. Easily a $5k job even doing most labor yourself and that still doesn't address some pretty big issues if you ever want to push for even more power later... open deck, crank hub fix, head work, etc.

    And yes, despite what people say, everything needs upgraded as you increase the power. Unless you just want a dyno queen show car you will want significantly more supporting mods as you increase the power. you'll need significant money into drive-train mods, bushings, and cooling. People make it all sound so easy but a vast majority of them aren't making anywhere near 700whp. They have their cheap single turbo kits on 15psi making 450whp because of 100 other things besides power they overlooked when doing the build...

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    Click here to enlarge Originally Posted by bnks334 Click here to enlarge
    newtis.info has the data you are looking for... but, slap in some new bearings and use some plasti-gauge on the journal. If it comes back between .0015" - .002" you're good. Re-seal the oil filter housing and oil pan. I wouldn't bother touching anything else. The front/rear main seals really don't fail unless you have a pcv issue. if you want to do the valve cover gasket then just buy a whole new generic valve cover. For 500whp goal I would not do much else to the engine itself. They are <$2k used don't overthink it and turn a cheap used engine into a money pit.

    If you want 700whp+ then you are now talking about rod, pistons, and messing with machine work. Gets very expensive quick. Easily a $5k job even doing most labor yourself and that still doesn't address some pretty big issues if you ever want to push for even more power later... open deck, crank hub fix, head work, etc.

    And yes, despite what people say, everything needs upgraded as you increase the power. Unless you just want a dyno queen show car you will want significantly more supporting mods as you increase the power. you'll need significant money into drive-train mods, bushings, and cooling. People make it all sound so easy but a vast majority of them aren't making anywhere near 700whp. They have their cheap single turbo kits on 15psi making 450whp because of 100 other things besides power they overlooked when doing the build...
    Thanks for the input. I'm in New Zealand so unfortunately used engines are not quite as easily available as they may be elsewhere. I picked up this 54k motor because it came complete, with turbos, and ALL pumps included for slightly less than what I'd expect to pay for for a bare motor.

    Is there a reliable source for generic cam covers that you can recommend if I need to replace it? Are they redesigned/improved somehow?

    On replacing the big end bearings, having a look at the clearances I can't obviously see how I'd do it without removing the pistons/rods. There is probably some trick to this I haven't seen Click here to enlarge

    Looks like my hitlist is:
    Check the main crank seals and replace only if necessary.
    Replace oil pan gasket.
    Seriously consider replacing the big end/rod bearings.
    Ensure the PCV system is working correctly / replace valve cover gasket.
    Replace any other rubber gaskets that make sense to do at this time (oil housing etc).

  19. #19
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    Is cracking in between the exhaust valves and spark plug normal on these cars? Or is this a case of a 200 lbs gorilla with a wrench?
    Click here to enlargeClick here to enlargeClick here to enlarge
    08' BMW 335xi, 153k Miles

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    Pictures of 2 cylinders?

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